Field of the Present Disclosure
The present disclosure relates to a burner array for a reduction reactor, and, more particularly, a burner array to allow hybrid (both oxidation and reduction reactions) reactions reactors including all oxidation reactors such as an incinerator, etc. and current coal gasification apparatuses to be converted to a reduction reactor where only a reduction reaction occurs, wherein in an reaction space of each burner of the array, only the oxidation reaction occurs, while in an reaction space of the reactor, only a reduction reaction occurs, the oxidation space being fluid-communicated with the reduction space, whereby various organic material wastes or coals may be completely decomposed without producing any toxic byproducts via the reduction reaction, and, thus, a synthesis gas (mixture gas of H2 and CO) with a high purity may be produced from the coals or organic material waste without a secondary treatment. Further, the present disclosure relates to a synthesis gas recycling system including the burner array for the reduction reactor.
Discussion of the Related Art
Generally, all types of industrially available oxidation reactors (combustion reactors) (for example, industrial waste incinerators, combined cycle power generation systems, hospital waste incinerators) mainly employ thermal-insulation materials with resistance against a lower temperature (below 1200° C.) oxidation environment, and a burner as a heat source. Such oxidation reactors decompose industrial wastes or hospital wastes using an oxidation reaction where the industrial wastes or hospital wastes are burned away to have smaller volumes in the oxidation reactors or incinerators. This may be due to the lack of knowledge about a decomposition using a reduction reaction.
However, when chlorine-containing waste materials such as PVC are decomposed using the industrially available oxidation reactors, much toxic dioxin are produced as a byproduct. Among kinds of the dioxin, tetrachlordibenzo p dioxine (TCDD) used as a defoliant or herbicide may kill twenty thousand persons each person having 50 kg weight with 1 g TCDD. The TCDD may be toxic as 1000 times as potassium cyanide.
Thus, the PVC may act as the greatest source of the dioxin among urban wastes. Further, when the PVC waste is incinerated, not only the dioxin but also at least 75 species of combustion byproducts are generated, including carcinogenic aromatic substances such as vinyl chloride monomers, chlorobenzene, benzene, toluene, xylene, and naphthalene. Further, when the PVC waste is incinerated, harmful ingredients, including phthalates as added plasticizers suspected as an endocrine disruptor, and a metal stabilizer such as lead, cadmium, etc. added to inhibit the decomposition rate may be discharged. Especially, since a large amount of heavy metals are added as reaction stabilizers, PVC may act as the greatest source of the lead and cadmium among urban wastes.
According to the hazardous substances series published by Food and Drug Administration, it is disclosed that during incineration of chlorine-containing organic compounds (PVC raw materials), dioxin is produced due to incomplete combustion of source gases, and/or fly ash heterogeneous reactions in cooler zones (250 to 450° C.). Further, during a post-combustion process with an operation temperature of about 250 to 300° C. after the incineration process, dioxin is again produced due to a catalytic effect of metal chloride in the fly ash.
Due to the above fact, although the dioxin is subjected to a secondary decomposition process at a high temperature over 1200° C., dioxin is more likely to be again produced as the operation temperature grows lower. During the incineration process, the decomposition may not occur in zones at which oxygen does not reach. Further, some of the zones should be subjected to a low temperature process. Thus, during the incineration process, it is impossible to completely suppress creation of dioxin.
Thus, many studies found out that during the waste incineration, a variety of secondary compounds by the oxidation are produced. For this reason, further studies focus on how to decompose the secondary compounds produced by the oxidation.
Also, in a coal gasification system such as IGCC (Integrated Gasification Combined Cycle) system, based on the recognition that a reduction reaction takes place above a certain temperature (about 1200° C.), a following process is developed: first, coal powders in a powder form of coals to be gasified are subjected to an oxidation in a single reaction space to generate a heat until the heat reaches a high temperature above 1200° C.; the oxygen supply is blocked when the heat reaches a high temperature above 1200° C.; thereafter, remaining not-yet combusted coal powders are subjected to the reduction reaction at that high temperature in the same reaction space, wherein both the oxidation and reduction reactions occur in the same space.
In the coal gasification system, the reduction reaction occurs as follows: a reduction-reaction type reactor: (ΔH: positive) above 1200° C.:C+H2O→CO+H2+122.6 kJ/molC+CO2→2CO+164.9 kJ/mol(—CH2—)+H2O→CO+2H2+206.2 kJ/mol(—CH2—)+CO2→2CO+H2+247.3 kJ/mol
The above reduction reaction is an endothermic reaction. In this connection, as shown in a graph of FIG. 8, for all of carbon-containing substances, above the temperature of 1200 to 1300° C., all carbons are converted into CO, and all hydrogen are converted into H2.
In the coal gasification system, there mainly occurs three reactions as follows: first, the coal powders and oxygen are reacted with each other as the exothermic reaction to generate a heat energy above 1200° C. using an oxidation reaction (in this connection, a hot steam H2O is added and thus the steam reaches the temperature above 1200° C., such that an inner temperature in the reactor reaches the temperature above 1200° C.); second, together with stop of oxygen supply, there occurs the reduction reaction at the temperature above 1200° C.; third, a secondary compound is produced at a relatively low temperature.
In this way, when the both the oxidation (heat energy generation) and reduction (gasification) reactions occur in the same space, not only the synthesis gas (mixture gas of H2 and CO) but also a sulfurous acid gas SO2 as the oxidation-created substance, suspended particles, nitrides NOx, various organic compounds (dioxin, hydrocarbon, volatile organic compounds (VOC)), mercury, arsenic, lead, cadmium, and the like are produced.
FIG. 1 shows a schematic view of a combustion state in a hot oxidation reactor with a general burner in accordance with a prior art. FIG. 2 shows a schematic enlarged view of a combustion state of the burner in FIG. 1.
As shown in FIG. 1, the combustion reactor 10 may have a general burner 20 disposed thereon, the burner 20 having a fuel feeding hole 22 and first oxygen feeding holes 23 formed therein. The combustion reactor 10 has a separate second oxygen feeding holes 11 formed at one side thereof. When the oxygen is supplied by a sufficient amount into the reaction space of the combustion reactor 10 via the first oxygen feeding holes 23 and second oxygen feeding holes 11, the combustion reaction may occur in the reaction space.
The conventional burner 20 may have a head portion 21 having a very short combustion space formed at one end thereof. Otherwise, the head portion 21 has no separate combustion space. Upon ignition of the burner 20, the flame from the head portion 21 directly reaches the substance to be decomposed in the reaction space in the combustion reactor 10 to combust the substance.
In the combustion reactor 10 using the conventional burner 20, the oxygen is present in the reaction space thereof, and the flame directly reaches the substance to be decomposed in the reaction space in the combustion reactor 10 to combust the substance. For example, a carbon-containing organic material CnH2n are combusted using the oxygen. In this way, both the oxidation reaction and reduction reaction (reduction reaction may partially occur in the region reach the temperature above 1200° C.) may occur in the same space. This may lead to creations of various oxides and secondary compounds.
Specifically, in addition to dioxin, aromatic carcinogens (PAHs) such as toluene, or naphthalene, benzene, vinyl chloride monomer, xylene, chlorobenzene, and a sulfurous acid gas SO2, a nitride NO2, carbon dioxide CO2, etc. may be produced. When such oxides and secondary compounds are discharged into an atmosphere in a non-treated state, serious atmospheric pollution and environmental pollution may be problematic. In this connection, it takes a significant amount of the treatment cost for filtering the compounds in an eco-friendly manner.
In addition, much fuel for the burner should be used for a good combustion state, and the oxygen should be continuously fed in order to directly combust the substance to be decomposed. This may lead to a significant amount of the fuel and oxygen cost.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.